The disclosure concerns a hydraulic assembly for modulating a brake pressure of a wheel brake, which can be coupled fluidically to the hydraulic assembly, of a motor vehicle brake system with electronic slip control.
Such hydraulic assemblies are known from the prior art. As an example, reference is made here to the disclosure of DE 197 24 166 A1. A hydraulic assembly known from this has a housing block through which brake fluid can flow and which is equipped with electronically controllable means for setting the brake pressure. As an example of a means for setting brake pressure, a pump unit comprising two piston pumps is shown. The two piston pumps are placed mutually opposite each other in alignment, in correspondingly provided receivers of the housing block. The respective pump inlet is protected, by means of a particle-filtering device, from particles penetrating the interior of the pump. In particular, metallic particles of high mechanical hardness may cause damage or premature wear on moving and/or sealing components of the piston pumps. The known particle-filtering device works mechanically and has a mesh screen. Mesh screens however have the disadvantage that they constrict the channel cross-section available for fluid flow, choking the throughflow, and hence constitute a flow resistance. Since this flow resistance depends greatly on the temperature and hence the viscosity of the brake fluid, at low ambient temperatures a particularly strong choking effect occurs. This in turn may lead to problems in brake pressure regulation, in particular on highly dynamic braking processes in which a relatively large quantity of brake fluid must be conveyed to the connected wheel brakes in a relatively short time. In addition, DE 10 2013 212 696 A1 describes a so-called soiling switch. This collects ferromagnetic particles in a fluid by means of an electromagnet and triggers a flushing process in a connected fluid system when the collected quantity of particles has reached or exceeded a pre-definable level.